Dr. Santangelo’s research interests are in the regulation of gene expression, and the pathogenesis of viruses, such as respiratory syncytial virus (RSV) and HIV. In order to develop new therapies for these pathologies, a fundamental understanding of their molecular mechanisms must be achieved. Dr. Santangelo’s contributions have focused on the development and engineering of new molecular imaging technology for uncovering these mechanisms. Molecular imaging provides both spatial and temporal information, at the single molecule, cell or organism level, which cannot often be obtained via biochemical assays. Specifically, he has focused on the development of two types of molecular imaging probes. The first type, single molecule-sensitive probes for imaging ribonucleic acid (RNA) molecules, allow for the study of messenger RNA regulation, an important part of gene expression, and the replication and assembly of RNA viruses. The second type of probe, positron-emission tomography (PET) probes, utilize antibodies and radioactive atoms to target viral infections and immune cells in live animals. These methods will provide new insights into the fundamental mechanisms of cancer pathogenesis and viral infections, which will lead to new drug targets in the future.